Réaction #70957

Équation de réaction

1,2-bis(2,5-dimethyl-3-thienyl)ethanedione

benzene

Potassium t-butoxide

benzene

→

25

Rendement 25.0%

3,4-bis(2,5-dimethyl-3-thienyl)cyclohexadiene

Rendement 25.0%

Conditions de réaction

Traitement

1. 1
   TempératureThe resulting orange solution was heated
2. 2
   Températureto reflux
3. 3
   workup.STIRRINGThe reaction mixture was stirred
4. 4
   Températureat reflux for 20 min, at which point the heating mantle
5. 5
   Autrewas removed
6. 6
   Températureto cool to room temperature
7. 7
   AutreThe reaction was quenched by the addition of water (50 mL)
8. 8
   Extractionextracted with Et2O (3×50 mL)
9. 9
   Lavagewashed with brine
10. 10
    Séchagedried over MgSO4
11. 11
    Filtrationfiltered
12. 12
    AutreThe solvent was removed under reduced pressure
13. 13
    Autrethe residue was purified by column chromatography through silica (1:9 EtOAc:hexanes)

Mode opératoire

Potassium t-butoxide (163 mg, 1.45 mmol) was added to a suspension of 1,4-butanebis(triphenylphosphonium)dibromide (537 mg, 0.725 mmol) in benzene (50 mL). The reaction was stirred for 45 min at room temperature. The resulting orange solution was heated to reflux and treated drop-wise with a solution of 1,2-bis(2,5-dimethyl-3-thienyl)ethanedione 23 (202 mg, 0.72 mmol) in benzene (25 mL). The reaction mixture was stirred at reflux for 20 min, at which point the heating mantle was removed and the reaction was allowed to cool to room temperature. The reaction was quenched by the addition of water (50 mL) and extracted with Et2O (3×50 mL). The organic extracts were combined, washed with brine, dried over MgSO4 and filtered. The solvent was removed under reduced pressure and the residue was purified by column chromatography through silica (1:9 EtOAc:hexanes) to yield 55 mg (25%) of 25 as a white solid. Mp=55-57° C. 1H NMR (CDCl3): δ=6.13 (s, 2H), 5.88 (m, 2H), 2.26 (m, 10H), 2.14 (s, 6H); 13C NMR (CDCl3) δ=137.8, 134.4, 133.9, 131.6, 127.4, 126.7, 22.7, 15.1, 14.0. MS (EI): m/z=300 (M+).

Source